The invention relates to a power liftgate assembly for a motor vehicle. More specifically, the invention relates to a power liftgate assembly providing lost motion for manual override.
Many motor vehicles including liftgates have the capability of driving the liftgate between its open and closed positions. When operating such an assembly, the operator merely needs to operate a switch and the liftgate latch will release and an electric motor will drive the liftgate between positions.
One disadvantage to many systems is the inability to adequately allow the operator the opportunity to manually move the liftgate. More specifically, the motor creates a resistance force that must be overcome in addition to overcoming the force assist struts that aid in maintaining the liftgate in an open position.
U.S. Pat. No. 6,283,535 discloses a vehicle liftgate power operating system. The operating system moves a hinged liftgate between its open and closed positions. An electric motor is operatively connected to a rack through a speed reduction device. The rack member is pivotally connected to an arm that is fixedly secured to the liftgate. A rotational force generated by the motor moves the rack axially, which is translated by the arm into a force directed at the liftgate pushing it about its pivot axis to move the liftgate between its open and closed positions. An electromagnetic clutch is required to break the torque transmitted from the motor to an output gear should manual operation of the liftgate be desired or required. The electromagnetic clutch is a heavy and costly item.
U.S. Pat. No. 6,142,551 discloses a vehicle liftgate power operating system. This system incorporates two motors that drive two linkages that are connected to the liftgate. The two linkages are arcuate and move through an arcuate path to move the liftgate between open and closed positions. This system does not, however, contemplate the manual movement of the liftgate.
U.S. Pat. No. 3,713,472 discloses a linkage system for a liftgate that is operable in a power mode and a manual mode. A drive gear provides power to move the liftgate between its extreme positions. An arcuate slot in the drive gear provides lost motion allowing the liftgate to be operated in manual mode, should it be desired to do so. This reference lacks in that the assembly is too large to be incorporated into the contemporary liftgate systems that require much of the liftgate mechanism to be housed in the headliner of the motor vehicle.
A power liftgate assembly is disclosed for moving a liftgate between an open position and a closed position. The liftgate is secured to a motor vehicle having a roof for pivotal movement about a substantially horizontal axis. The power liftgate assembly includes an elongated bracket that is fixedly secured to the roof of the motor vehicle. The elongated bracket extends between first and second ends. A motor is fixedly secured to the elongated bracket. A slide operatively engages the motor. The slide moves along the elongated bracket. An articulated bracket is connected to the slide and moves with the slide. The articulated bracket includes a slot that extends therealong to provide lost motion between the articulated bracket and the slide. An arcuate bracket extends between the articulated bracket and the liftgate for receiving the motion of the articulated bracket and for moving the liftgate in response thereto.